The present invention relates to an electron beam drawing apparatus and a method of electron beam drawing.
An electron beam drawing apparatus is an apparatus performing a predetermined drawing on a sample by irradiating an electron beam to a predetermined position, performing the irradiation after moving an irradiated portion and repeating the above steps (This technique is described in, for example, Japanese Unexamined Patent Publication No. 117325/1989). A drawing performed by this apparatus has advantages wherein a mask is not necessary and a high resolution is provided, for example, in comparison with a stepper, for example. In recent years, the electron beam drawing apparatus has been widely spread in a trial manufacture of a micro device, manufacturing of a special purpose (assigned) application specific integrated circuit (ASIC) and the like.
Conventionally, when an irradiated position of an electron beam is moved, the electron beam is deflected such that the electron beam does not reach a sample (blanking of the electron beam). Further, the electron beam drawing is performed such that the electron beam again reaches the sample when the irradiated position has been moved.
Meanwhile, a technology of drawing using an electron beam is considered by dispensing with the blanking to promote drawing speed. That is, the irradiated position of the electron beam is moved while the electron beam is kept irradiating on the sample.
However, when the irradiated position of the electron beam is moved in a state wherein the electron beam is kept irradiating on the sample in such a way, there is a nonuniformity of the amount of irradiating the electron beam in the moving direction of the electron beam at a start point and an end location of drawing. For example, at the start point of drawing, the amount of irradiating the electron beam at a position in the moving direction of the electron beam is larger than that at another position disposed opposite to the moving direction of the electron beam. The nonuniformity of the amount of irradiation of the electron beam causes dimming of a pattern edge.
An explanation will be given thereof as follows. For example, suppose that the width of a beam spot is determined as W and the electron beam is moved from left to right with a moving speed of v. When the electron beam begins to irradiate and thereafter, the electron beam is moved from left to right, the far left portion of the beam spot is in a state in which the electron beam is not irradiated at the instance of moving the electron beam. Similarly, a portion of the beam spot within a distance of w (w&lt;W) from the center of the spot wherein the far left side of the spot is at a position having a distance of w when the electron beam begins to irradiate, is irradiated for a period of time of w/v. Therefore, the farther the left side portion is disposed, the shorter the time of irradiating the electron beam. Such a nonuniformity of the amount of irradiating the electron beam causes the dimming of a pattern edge. This is the same with respect to a finish portion of irradiating the electron beam.